1. Field of the Invention
The invention relates generally to the field of accelerator mass spectrometry. More particularly, the invention relates to accelerator mass spectrometers employing a multicharged ion source.
2. Discussion of the Related Art
The main difficulty in single atom detection of C-14 arises from the isobaric interferences due to N-14 atomic ions and 12CH2 and 13CH molecular ions. In conventional accelerator mass spectrometry (AMS) the approach consists of using a negative ion source to eliminate the 14N contamination, since it does not support a stable negative ion, accelerating the negative ion beam in a tandem accelerator to high energy (few MeV), and then dissociating molecular ions isobaric with 14Cxe2x88x92 also present in the ion beam either in a foil or gas target. Subsequent stages of electrostatic and magnetic analysis are then used to isolate the 14C ions prior to their detection. Conventional AMS requires large, nuclear physics scale facilities, with correspondingly high cost, which are usually not dedicated to a single task, and entails time consuming sample preparation prior to the actual measurements, and so is not suited to quasi-real time monitoring Of C-14 levels.
The invention includes an apparatus and method for the detection of carbon-14 and other rare isotopes where molecular ion isobaric interferences are a problem, and where interfering atomic isobars do not form stable negative ions. In this invention, large nuclear physics scale facilities such as used in conventional accelerator mass spectrometry (AMS), for example, are not needed.
These, and other, goals and embodiments of the invention will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following description, while indicating preferred embodiments of the invention and numerous specific details thereof, is given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the invention without departing from the spirit thereof, and the invention includes all such modifications.